1. Field of the Invention
The present invention relates to a gearbox for an automotive vehicle.
2. Description of Related Art
Typically, gearboxes are used to increase torque while reducing the speed of a prime mover output shaft. This means that the output shaft of a gearbox will rotate at a slower rate than an input shaft. This reduction in speed will produce a mechanical advantage, causing an increase in torque. Alternatively, gearboxes can be setup to do the opposite and provide an increase in output shaft speed with a reduction of torque. Some of the simplest gearboxes merely change the physical direction in which power is transmitted.
Gearboxes generally include a housing containing a pinion gear that is driven by an input shaft. The pinion gear, in turn, drives an output member having an output flange. The output flange is disposed outside of the housing and is adapted to be coupled with a vehicle driveline component. The pinion gear includes a gear portion operatively engaged with the input shaft and an axially extending gear stem that is externally splined along its length. The output member includes an axially extending output stem that is internally splined along its length. The gear stem extends through the output stem and is in splined engagement therewith such that rotation of the pinion gear by the input shaft causes the output member to rotate. The pinion gear and output member are supported by a pair of axially spaced apart bearings disposed radially between the output stem and the housing. A distal end of the gear stem includes a threaded portion for receiving a pinion nut to secure the output member to the pinion gear.
Over time, due to vibration or the like, it is possible that the pinion nut will back-off or loosen which allows for axial play between the output member and the pinion gear. There are a variety of known ways to secure the pinion nut to the gear stem to prevent the pinion nut from loosening over time. For example, the pinion nut may be staked to the gear stem, however, most stakeable nuts have separate features for tightening the nut and staking the nut such that more space is required for these types of nuts. A castle nut requires a separate piece, such as a cotter pin, which is deformed between the gear stem and slots or other hard features on the castle nut. A prevailing torque nut includes a plastic insert or noncircular head to increase the friction between the nut and the gear stem. A crush sleeve is elastically deformed and provides a preload against the nut that inhibits loosening of the nut. Prevailing torque nuts and crush sleeves, however, can only be used once. An adhesive, such as Loctite®, can also be used but the adhesion between the nut and gear stem may be broken under conditions of vibration in high stiffness systems. Finally, there are different thread forms that inhibit loosening of the nut through added friction between the nut and the gear stem.
Each of these previously mentioned types of nuts and nut retention methods have inherent drawbacks. It is therefore desirable to provide a simple and compact nut that can be secured to a threaded shaft to secure two members together and will not loosen over time due to vibration or the like. It is also desirable that the nut be removable from the threaded shaft and can be reused.